Chlamys hastata ellisi Hertlein & Grant, 1972
HERTLEIN, L. G. & U. S. GRANT IV. 1972. The Geology and Paleontology of the marine Pliocene of San Diego, California (Paleontology: Pelecypoda). Memoirs of the San Diego Society of Natural History, Memoir 2, Part 2b. pp. 143-409, pls. 27-57. [p. 190, pl. 31, figs. 2, 3; pl. 34, fig. 6]
1972 Chlamys (Chlamys) hastata ellisi Hertlein & Grant, 1972
L. G. Hertlein & U. S. Grant IV, 1972, plate 31.
L. G. Hertlein & U. S. Grant IV, 1972, plate 34.
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«Description. — Shell characters similar to those of Chlamys hastata but differing in the presence of fine honeycomb-like tesselations covering the interspaces and sides of the ribs, but obscured on the tops of the ribs where covered by strong imbricating spinose sculpture. Length, 66 mm; height, 68.5 mm.
Type specimen. — Holotype, a right valve. Invertebrate Paleontology Collection, Los Angeles County Museum. Type locality. — Loc. 305 (LAM), 2400 feet east and 1350 feet south of the northwest corner of Sec. 8, T. 19 S., R. 2 W., San Bernardino Base and Meridian (see U. S. G. S. topog. map, San Ysidro quad., ed. 1943). Range. — Known with certainty only from strata of middle Pliocene age at the type locality. Remarks. — In addition to the holotype a right valve, 31 mm high, and two small left valves, the larger one 20.8 mm high are referable to this new subspecies. The entire surface of left valves is covered with minute tesselations. This sculpture, composed of a layer of minute scaly imbrications, is usually preserved in the interspaces but sometimes covers the ribs as well. Often the scaly honeycomb-like material is mostly gone and the interspaces retain only a pattern of minute reticulation. This type of sculpture ("Gittersculptur" of Philippi (332) is present on C. islandica and allied forms. It also occurs on many species in other groups of scallops, including Manupecten, Patinopecten and Swiftopecten. It may be a primitive character. This minute sculpture may easily disappear with erosion and it is quite possible that some fossil specimens lacking perfect preservation in the present as well as in other collections, and referred to Chlamys hastata or C. h. hericius, may represent C. h. ellisi n. subsp. The only reliable basis for separating the present new subspecies form C. hastata rests entirely on the presence and recognition of the surficial tesselated sculpture. The minute sculpture of the present subspecies is similar to that of the form described as Pecten islandicus pugetensis (333). As mentioned by Gregg (334), the presence of minute tesselation was not mentioned in the original description by Oldroyd. The ribs of C. hastata pugetensis are more rounded than those of C. hastata, those on each valve are nearly equal in size, and the fasciculi are minutely spinose. The interior of Recent shells is often ornamented, especially around the ventral margin, with dark red or red-orange color. Chlamys hastata pugetensis is generally reported to be smaller than C. hastata, C. h. ellisi n. subsp., and C. h. hericius. Henderson (335), however, reported a specimen 77 mm high and long from deposits of Pleistocene age on Big Hope Island in Puget Sound. We have examined six specimens from the type lot of C. h. pugetensis, the largest of which is 43 mm high. The minute tesselated sculpture on some of these occurs over nearly the entire valve but disappears near the ventral margin. Four other Recent specimens from Puget Sound, in the collections of the California Academy of Sciences, likewise bear this characteristic minute sculpture. We also have seen specimens from Duxbury Reef, Marin Co., and from Monterey Bay, California, which retain traces of this tesselated sculpture. One Recent specimen from Braca Point, Washington, 51 mm high, possesses typical sculpture of C. h. pugetensis until it is 26 mm high and then follows sculpture of minute oblique groovings such as that on C. h. hericius, which it resembles in general features. Chlamys hastata pugetensis is reported living from Sitkalidak Island, off eastern Kodiak Island, Alaska, to Newport Bay, Califronia, from low tide to 91 meters (50 fathoms). It has been reported as a fossil by Gregg (1938) from strata of "presumably Pliocene" age. Deadman Island, San Pedro, California, and questionably by Grant and Gale (1931, p. 168) from strata of middle Pliocene age southeast of Pico Canyon, Los Angeles Co., California. It appears that since Pliocene time the members of the Chlamys hastata group bearing honeycomb-like tesselations have been reduced to one subspecies, which is smaller, less numerous, and in general has become restricted to cooler waters.» LEO GEORGE HERTLEIN & ULYSSES SIMPSON GRANT IV, 1972
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«Comparison.— "The only reliable basis for separating C. hastata ellisi * * * from C. hastata rests entirely on the presence and recognition of the surficial tesselated sculpture.
"The minute sculpture of the present subspecies is similar to that of the form described as Pecten islandicus pugetensis* * * The ribs of C. hastata pugetensis are more rounded than those of C. hastata, those on each valve are nearly equal in size, and the fasciculi are minutely spinose.*** "Chlamys hsstata pugetensis is generally reported to be smaller than C. hastata, C. h. ellisi n. subsp., and C. h. hericius." (Hertlein and Grant, 1972, p.191) Geographic distribution.— Southern California. Geologic range.— Pliocene. Occurrence in California.— San Diego Formation.» MOORE, E. J. 1984. Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae. United States Geological Survey Professional Paper, 1228-B: iv + B1-B112, figs. 1-2, pls. 1-42. [p. B24]
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Chlamys (Chlamys) hastata ellisi Hertlein and Grant; E. J. Moore, 1984, Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae, plate 5, figure 9.
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